This is a parallel, randomized, bioavailability and safety study in normal, healthy, postmenopausal women or had bilateral oophorectomy with a hysterectomy. One objective of the study is to examine the bioequivalence of transdermal estradiol when administered as Estrofilm 1% gel once a day compared with Estraderm 0.05mg patch administered twice daily. Serum estradiol levels will be used to calculate the area-under-the curve (AUC) to establish bioequivalence. Another objective of the study is to examine the safety of Estrofilm.